The "tragedy of the commons" thought experiment (described by Garrett Hardin in an eponymous 1968 article) is frequently used as an argument for laissez-faire capitalism.

Hardin argued that an individual townsperson using the commons to graze sheep (or horses or yaks or whatever) will always see that the immediate benefit to himself of adding another animal far outweighs the damage he'll do to the commons by putting Old Paint out there to feed. He gets the benefit: everyone else gets the cost.

Now, most of the time that's used to support a position like, "Hey, we've got these commons that we can't all use as much as we'd like. Maybe we should have some rules about who gets to use them when?"

If you're a hard-core Adam Smithish libertarian, however, you turn that thinking on its head. You say, "Maybe we'd be better off without any commons."

The underlying principle is that if you've got some allocation of resources that isn't working right, you should look for some area that isn't controlled by a market of private owners. In this case, the commons are, by definition, not owned by anybody -- so there's nobody who has a direct personal stake in protecting them, so nobody does. If the commons had an owner, that person could police them and make sure everybody behaved themselves, in exchange for a fee for their use.

This idea works reasonably well for something like grazing rights -- unless you've got some whacked-out neoconservatives in your government who are keen to keep lots of land in public ownership and rent it out cheap to ranchers, as the United States does -- but falls apart for things like air and water pollution, where what you do on your land has an inevitable effect on your neighbours'.